Apparatus for measurement of ducted air

ABSTRACT

Apparatus for measurement of airflow in a duct is described. The apparatus combines a Pitot tube, sensing apparatus, control apparatus, a display, control switches and a handle into a unitary structure that is holdable with a single hand while performing obtaining measurement data.

RELATED APPLICATIONS

This application claims the benefit of Provisional Patent ApplicationNo. 61/463,549, filed Feb. 19, 2011, titled System of Wireless Sensorswith Wearable Controller.

This application also claims the benefit of and is acontinuation-in-part of my prior application Ser. No. 13/136,814 filedon Aug. 11, 2011 that claims the benefit of Provisional PatentApplication Ser. No. 61/401,336, filed Aug. 11, 2010, entitled WearableWireless Instrument System; and that also claims the benefit ofProvisional Patent Application Ser. No. 61/463,549, filed Feb. 19, 2011,entitled System of Wireless Sensors with Wearable Controller. Thedisclosures of those prior applications are incorporated herein byreference.

FIELD

The present invention relates to measurement instruments, in general,and to apparatus for performing measurements on airflow inside a duct,in particular.

BACKGROUND

Measurement problems are important to the HVAC industry. Measurementdisputes are often at the heart of conflicts over HVAC performanceissues such as uncomfortable buildings, inefficient energy performance,and inability to maintain specified parameters such as adequate positivepressure in hospital operating rooms. These conflicts frequently resultin anger, confusion, disputes, cancelled contracts, lawsuits, mediation,and unhappy building owners, tenants, and workers. Contributing to theseconflicts is that measurements of HVAC-related building parameters suchas air and water temperature, humidity, pressure, velocity, and flow areperceived to be inaccurate and unreliable, so dissatisfied parties oftenchallenge their validity.

Fans create pressure differences, which force air to flow through theduct system of a building. Fans in the air handling unit (AHU) generatethe energy necessary to overcome the duct system's resistance toairflow. Resistance is offered by filters and heat exchange coils.Straight ducts have resistance in proportion to their length. Bends andsize changes increase resistance to flow. Diffusers (grilles, outlets)offer the final resistance before the air reaches the occupied spaces ofa building. After exposure to humans and machines, the stale, warm,humid air faces additional resistance as it is pulled back to the AHUthrough the return air duct system.

HVAC engineers specify the critical parameters of a building's ductsystem, including the range of airflow volume, temperature, humidity,and pressure that must be present at each point in the system. Airbalancers must verify that the HVAC system meets the specifications.They measure the state of the system as installed, issue correctiveaction requests as necessary, and then tune the system to achieveoptimum comfort and energy efficiency within the range of conditionsspecified.

Air balancers must measure critical air parameters at many key placesthroughout the building's duct system, including right at the AHU, inthe main duct, at the entrance to key branch ducts, such as the ductsfeeding each floor of a building, and in the various ducts supplyingdiffusers in the occupied spaces. The measured air volumes are collectedand compared and analyzed in charts to account for every CFM (cubic feetper minute) of air generated by the fan. Leaks are detected and fixed.Rotational speeds (RPM) of fans are adjusted. Valves, dampers, andgrilles are adjusted.

Flow and airflow are industry terms that relate to the volumetric rateof fluid flow expressed in units such as cubic feet per minute (CFM).Airflow is usually not measured directly. It is usually calculated bymeasuring the velocity of air at multiple points in a cross-sectionalplane, calculating an average velocity at the plane, and thenmultiplying by the known area of the cross-section. The plane wheremeasurement takes place might be across an air duct, in a duct-shapedprobe like a capture hood, or at the opening of a fume hood, door, orwindow.

A velocity traverse or “duct traverse” is one of the most complicatedand arduous procedure in the air balancing field.

A “duct traverse” is a series of measurements at a particular point in aduct to determine the air volume in cubic feet per minute (“CFM”) andthe air velocity profile in feet per minute (“FPM”). It is usuallydesirable that additional parameters be measured at the same location,including the static pressure, which is the pressure between the airinside the duct and the pressure in the building, and air temperature(dry bulb). Sometimes air moisture content is also measured, in terms ofwet bulb temperature or dew point or percent relative humidity or grainsof water per cubic foot.

The term “traverse” as used herein means the measurement of everyparameter of interest at a particular duct location.

Not only are traverses required in multiple locations of a building,traverses are often required to be performed multiple times over days orweeks at the same location, because the duct system must be tested undervarious conditions. Nighttime conditions are controlled differently fromdaytime conditions. Seasons vary and the load of temperature andhumidity stress on the building varies. There are often fire and/orsmoke control modes with special duct requirements. These requirementsmean that duct traverses are among the most frequently performedprocedures of air balancing.

Measurement tools and techniques have changed very little in the lastcentury. A Pitot tube is still the velocity probe of choice. The Pitottube is actually two tubes within a probe shaft that conduct twodifferent air pressures from one end to the other. There are twoorifices on one end and two ports on the other end. When the tip of aPitot tube is properly oriented with its tip facing the direction ofairflow, the air colliding with the tip causes Total Pressure, while theair moving parallel to the shaft causes Static Pressure. Themathematical difference between Total Pressure and Static Pressure iscalled Velocity Pressure. If Velocity Pressure is known, along withtemperature and barometric pressure, which determine the density of air,then the following popular equation, derived from fundamental laws ofphysics, provides the precise velocity of the moving air:

V=1096.7×square root of (VP/d),

where:

-   V is velocity in feet per minute-   VP is velocity pressure in inches of water column-   d is density of air in pounds per cubic foot=1.325×BP/T, where:-   BP is barometric pressure in inches of mercury-   T is absolute temperature=degrees Fahrenheit+460

A Pitot tube that comprises two tubes, one to conduct total pressure andthe other to conduct static pressure is also referred to as a“Pitot-static tube”. The term “Pitot tube” as used herein is intended tobe inclusive of the so-called “Pitot-static tube.”

Some velocity probes are based on differential pressure like the400-year-old Pitot tube, but they have “lee side” orifices instead ofstatic pressure orifices, so the differential pressure generated is notthe same as traditional velocity pressure. However, velocity can stillbe calculated using the equation above, with only the addition of aconstant factor K that can be empirically determined such that theequation becomes:

V=K×1096.7×square root of (VP/d).

A duct traverse is performed as follows. A technician first measures thelength and width of a rectangular duct, or the diameter of a round duct,and calculates the cross-sectional area, adjusting for the thickness ofthe duct walls and any insulation or other internal obstructions. Thenhe consults a table provided by an engineering society, such as ASHRAE,for the locations of the points in a matrix on the duct cross-sectionalplane at which air velocity must be known in order to make an accuratecalculation of average air velocity. The technician drills holes in theduct to allow the Pitot tube to be positioned at the each point in thematrix. It is convenient to think about horizontal and vertical planesacross the duct. The technician marks his probe with tape so he can seehow far into the duct to insert it to reach each traverse point.

To perform the measurements in a typical non-residential site, thetechnician usually has to stand on a high ladder, with his head abovethe ceiling tiles, and balance precariously while manipulating tools inboth outstretched hands. In one hand is the meter. Connected to themeter with tubes is a Pitot tube probe, which is inserted into the ductand placed at the point of interest. Holding the Pitot tube as steady aspossible, the technician pushes a button on the meter to make ameasurement. Then the technician moves the Pitot tube probe to the nextpoint and makes another measurement. The technician must manipulate themeter with one hand to press the control keys while manipulating thePitot tube with the other hand and keeping the tubes from swinging andgetting tangled.

The technician then makes a velocity measurement at each traverse point,one after the other, recording or storing each reading as he goes.Usually, between 16 and 100 measurements are required, depending on thesize of the duct, each one taking a few seconds or several seconds. Wheneach point in the matrix has been measured, the Pitot tube is withdrawfrom the duct. The temperature and/or humidity probe is withdrawn fromthe duct. The holes are plugged to prevent air leaking out. The averageof all measurements is recorded as the average velocity at that ductcross-section. When multiplied by the cross-sectional area, thevolumetric airflow is determined.

After the traverse measurements, the technician must measure the staticpressure in the duct at that location. Traditional instruments will notallow static pressure to be measured with the same setup as velocity.The technician must remove the Pitot tube from the duct, change the airhose attachments, and change the mode on the meter. The technician thenre-inserts the Pitot tube, or a different probe for measuring staticpressure, back into the duct. A series of measurements are made todetermine the most representative static pressure at that location, andit is noted.

Beyond the basic set-up procedures of determining duct size, determiningmatrix points, and drilling duct holes, these steps are required: attachtemperature probe to meter, set meter to temperature mode, inserttemperature probe in duct, measure temperature, change meter mode tovelocity, attach pressure tubes to meter and Pitot tube, insert Pitottube into duct, measure velocity at traverse points and store data inmemory for review and statistics, withdraw Pitot tube from duct, changetubes at meter and at Pitot tube for static pressure, change meter modeto static pressure, insert Pitot tube into duct, measure staticpressure, remove Pitot tube from duct.

There are well known problems with the duct traverse procedureincluding, but not limited to the time consuming nature of performingthe measurements; the precarious manner in which the measurements aremade; and the multiple steps required.

Conventional commercially available instruments are designed to measureand display only one parameter at a time, and require regular manualoperation to even do that. A typical hand-held meter or instrumentcomprises a plastic case enclosing a printed circuit board withmicroprocessor-controlled electronics, memory, one or more sensors, anda display. A sensing probe is connected using cables, wires, tubes, orother means. Various probes, large and small, are designed to collectenvironmental samples for sensing, measurement, display, and storage.The user often must wait between 2 and 8 seconds for the meter togenerate a reading. The reading is then displayed by the meter and theuser can either write it down or store it in the memory of the meter.All of this is required to determine the velocity at a single point inthe duct.

Foil types of velocity probes are sometimes preferred because they areeasier to insert through a hole into the duct, not having the bend ofthe traditional Pitot tube. Unlike Pitot tubes, foil-type probes canalso measure negative velocity, the velocity of air moving in theopposite direction due to eddies near duct discontinuities. However, thefoil-type of probe has a lee-side orifice instead of a true staticpressure orifice, so the static pressure measurement of a completetraverse requires the replacement of the velocity probe with atraditional static pressure probe, known as a “static tip”. Thisrequires time and limits the productivity of the technician, who maydecide to skip the measurement or estimate the static pressure.

A problem of conventional practice is that the traverse measurementsstored in the conventional meter are required at a different physicallocation. Conventional practice is for the meter to be brought to atable where the stored data is either transferred manually to a computeror report form, or the data is loaded electronically into a personalcomputer for subsequent report generation.

Typical meters are generally so large and heavy that they require atechnician to devote a hand to hold them and another hand to presscontrol keys. With difficulty, a technician learns to hold an instrumentin his palm while fingering the keys with the thumb of the same hand.That hand is not available to steady or brace the technician who standsin a precarious situation. Accordingly, there is a need for instrumentsthat are small and light and able to be mounted and supported withoutrequiring a human hand and arm.

Airflow meters provide low velocity accuracy. Typical accuracies arespecified as 3%+/−7 fpm. A reading of 500 FPM could really be 478 to522. But at 100 FPM, the velocity could really be 90 or 110, and at 50FPM, the velocity could really be 41.5 or 58.5. That not consideredaccurate enough.

Measurements may be inaccurate for several reasons that are independentof metering accuracy. More specifically, accuracy is lost when physicalstress causes the technician to inadvertently move the velocity probeduring measurement or hold the probe in the wrong location; accuracy islost when the long, dangling rubber hoses between the instrument and theprobe are allowed to swing, causing waves that affect the pressuresensors; accuracy is lost when the technician rushes through theprocess, taking too few velocity measurements or taking other shortcuts;and accuracy is lost when duct air temperature is often ignored due tothe difficulty and time required to place and hold the temperature probefor a proper measurement. The typical probe is attached to the meter viaa coiled cable.

Accuracy is also lost when the velocity profile is not uniform enough tomeet industry standards. The industry-prescribed matrix locations weredeveloped over many years and much research to ensure an accurate resultof traverses. Industry standards forbid the performance of a traverse inareas where fans, dampers, louvers, duct bends, or otherdiscontinuities, cause air turbulence and uneven airflow. In theproscribed sections of duct, air eddies and reverse currents can exist.Velocity traverses in these areas, if conducted on the standard matrix,will not be accurate. It is necessary that air passing through suchdiscontinuities be allowed to even out over many feet of straight duct,after which a typical velocity profile is achieved. However, the realityis that architects and engineers are not required to provide such aproper location for a duct traverse, and they often cannot be found. Inthese cases technicians are forced to measure at the undesirable profilepoint. The accuracy of the average velocity calculated would be improvedif the number of measurement points in the matrix were increasedsubstantially. Current industry standards allow that—specifications arefor the minimum number of readings. However, technicians are reluctantto do that because the procedure is already so time-consuming.

SUMMARY

In accordance with an embodiment, handheld measuring apparatus isprovided comprising an air velocity probe; and a handle affixed to theair velocity probe, the handle configured such that the air velocitytube is graspable in a single hand for taking measurements in anairstream.

Pressure sensing apparatus is coupled to the air velocity probe andcarried by the handle, the air velocity probe, the handle and thepressure sensing apparatus comprising a unitary apparatus configured tobe held in a single hand.

The unitary apparatus further comprises a microcontroller coupled to thepressure sensing apparatus.

Display apparatus in communication with the pressure sensing apparatusto display the measurements is provided in an embodiment. The displayapparatus is coupled to the microcontroller for displaying themeasurements. The display apparatus is carried by the handle andcomprises a portion of the unitary apparatus. In at least oneembodiment, the display is adjustable for viewing. Movable apparatus iscoupled to the handle and supporting the display.

A memory is provided for storing the measurements.

In various embodiments, one or more switches are carried by the handleto control operation of the apparatus.

In a preferred embodiment, the air velocity probe comprises a Pitottube. The air velocity tube comprises a total pressure outlet and astatic pressure outlet.

The pressure sensing apparatus comprises: one or more solid statepressure sensors; and a selectively operable valve arrangement coupledto the air velocity probe and to the one or more solid state pressuresensors. A microcontroller is coupled to the pressure sensing apparatusand to the selectively operable valve arrangement for controllingoperation of the apparatus. The selectively operable valve arrangementcomprises a plurality of selectively operable valves coupled to one ormore pressure sensors.

In an embodiment, apparatus is provided to measure velocity pressure andstatic pressure in air handling systems. The apparatus comprises: aPitot tube for insertion into a duct. The Pitot tube comprises a totalpressure tube having a total pressure tube outlet, and a static tubehaving a static tube outlet. A sensing module is provided having a firstinlet coupled to the Pitot tube total pressure outlet and a second inletcoupled to the static tube outlet. The sensing module is operable toconcurrently measure air velocity pressure and air static pressure inthe duct. The apparatus further comprises a handle carrying the Pitottube and the sensing module. The Pitot tube, the sensing module and thehandle are arranged to provide a measuring unit holdable and operable inone hand. The sensing module comprises first and second solid statedifferential pressure sensors. The sensing module comprises valvingapparatus disposed between the first and second inlets and the first andsecond solid state differential pressure sensors. The sensing modulecomprises a processor in communication with the pressure sensors andoperable to control the valving arrangement.

One embodiment comprises a control and display module; and the sensingmodule is in communication with the control and display module.

In an embodiment, a display is carried by the handle to displaymeasurements and the display is positionally adjustable.

In various embodiments one or more switches are carried by the handlefor controlling operation of the apparatus.

In various embodiments, the sensing module comprises first and secondsolid state differential pressure sensors. The sensing module comprisesvalving apparatus disposed between the first and second inlets and thefirst and second solid state differential pressure sensors. The sensingmodule comprises a processor in communication with the pressure sensorsand operable to control the valving apparatus. The sensing module is incommunication with a control and display module.

The sensor module and the control and display module are cooperativelyoperative to automatically concurrently measure air velocity pressureand air static pressure at predetermined time intervals. The timeintervals are selected to provide a duct traverse.

In yet a further embodiment, apparatus is provided to measure velocitypressure and static pressure in air handling systems, the apparatuscomprises: a Pitot tube for insertion into a duct, the Pitot tubecomprising a total pressure tube having a total pressure tube outlet,and a static tube having a static tube outlet; a module having a firstinlet coupled to the Pitot tube outlet and a second inlet coupled to thestatic tube outlet, the module operable to concurrently measure airvelocity pressure and air static pressure in the duct, the modulecomprising a display to display measurement data; and a handle carryingthe Pitot tube and the module. The Pitot tube, the module and the handlearranged to provide a measuring unit holdable and operable in one handwith the display viewable by a user of the apparatus.

The module comprises at least one processor to perform predeterminedcalculations utilizing pressure measurements received at the first andsecond inlets. The module comprises a memory; and the processor storescalculated results in the memory.

The apparatus further comprises a display; and the processor is operableto display predetermined ones of the calculated results on the display.

The module is operative to automatically concurrently measure airvelocity pressure and air static pressure at predetermined timeintervals. The time intervals are selected to provide a duct traverse

BRIEF DESCRIPTION OF THE DRAWING

The invention will be better understood from a reading of the followingdetailed description taken in conjunction with the drawing figures inwhich like designators are used to identify like elements, and in whichthe various drawing elements are not drawn to scale, and in which:

FIG. 1 illustrates a prior art Pitot tube;

FIG. 2 is an isometric view of an embodiment in accordance with theprinciples of the invention;

FIG. 3 illustrates a portion of the embodiment of FIG. 2 in greaterdetail;

FIG. 4 is a top view of the portion shown in FIG. 3;

FIG. 5 is a side view of the portion shown in FIG. 3;

FIG. 6 illustrates the velocity sensing module of FIG. 2 in greaterdetail;

FIG. 7 is a block diagram of the velocity sensing module of FIG. 4;

FIGS. 8A, 8B, and 8C illustrate representative display formats;

FIG. 9 illustrates the apparatus of FIG. 2 in use;

FIG. 10 illustrates a second embodiment;

FIG. 11 illustrates air flow in a duct; and

FIG. 12 illustrates a method.

DETAILED DESCRIPTION

FIG. 1 shows a prior art Pitot tube 100. Pitot tube 100 includes portion101 that is oriented to be in an airflow, and a main shaft portion 103that is extended into the airflow. Pitot tube 100 comprises a totalpressure Pitot tube 105 and a static pressure tube 109. Total pressuretube 105 includes an aperture disposed at end 107 of Pitot tube 100 anda total pressure outlet 117 at its other end. Static pressure tube 109comprises one or more apertures 111 disposed on Pitot tube end portion101 and terminates in a static pressure outlet 115.

Turning now to FIG. 2, a first embodiment of a structure 200 includingPitot tube 100 is shown. Pitot tube 100 is provided with a handle 201that permits Pitot tube 100 to be more easily manipulated in an airflowsuch as that in a duct. Handle 201 carries Pitot tube 100, a velocitysensing module 401 and a control and display module 203.

Structure 200 permits one to advantageously perform a velocity traversewhile using only one hand, allowing the other hand to be available forholding another tool or for grasping a fixed object for bracing andsafety.

FIGS. 3, 4 and 5 illustrates the handle portion 205 of structure 200 ingreater detail. FIG. 3 illustrates the handle portion 205 withoutcontrol and display module 203 to permit details of apparatus 317 thatretains control and display module 203 to be easily seen.

Handle 201 in the embodiment shown is machined from a single block ofnylon with several appropriate features. Handle 201 has its outersurface 301 shaped to conform to a human hand in similar fashion as abicycle handle bar grip. Handle 201 includes a slot 303 into which aPitot tube 100 can be inserted such that main shaft portion 103 is heldtightly. Handle 201 has a hole that is not shown that extends from thebottom of slot 303 through which static pressure output tube outlet 115extends, providing axial and rotational control of Pitot tube 100. Aspring bearing 305 is carried by handle 201 and when Pitot tube 100 hasbeen pressed down into slot 303, spring bearing 93 presses tightlyagainst the top of Pitot tube 100, retaining it in slot 303.

Total pressure outlet 117 lays in slot 303, where it is connected to asemi-flexible tubing connector 307. Semi-flexible tubing connector 307extends in slot 303 and through a hole 309 in end 311 of handle 201 to atotal pressure inlet port 403 of velocity sensing module 401. Staticpressure output port 115 of Pitot tube 100 is connected by asemi-flexible tube 313 to the static pressure inlet port 405 of velocitysensing module 401. Tubes 307, 313 are fashioned of a material such asneoprene rubber which are easily and commonly installed and uninstalledon Pitot tubes and similar probes in the field. Tubes 307, 313, whilebeing somewhat flexible, are stiff enough that velocity sensing module401 does not move during measurement.

Structure 200 supports the vast majority of existing Pitot tubes andfoil-type probes. Such probes vary greatly in length, but the dimensionsof the main shaft portions 103, static pressure outlet ports 115, andtotal pressure outlet ports 117 are virtually identical, such thatstructure 200 is adapted to securely carry such Pitot tubes andfoil-type probes.

Control module 203 is mounted on flexible support arm 315. Support arm315 is a gooseneck type of support tube in the embodiment and includes aclip retainer 317 to retain control module 203. Control module 203 mayinclude a display and may be moved as desired so that the display facesthe user such that measurement results can be viewed by the user withoutmoving his head from the task of positioning Pitot tube 100.

Handle 201 carries contact switches 286 and 287. Contact switches 286,287 have electrical leads that exit the nylon handle in cable 285 andconnect to velocity sensing module 401. Contact switches 286 and 287 arein a position to be pressed and activated by a user's thumb to inputcommands to control module 203 for actions such as mode, view, andstoring of readings. Velocity sensing module 401 detects a operation ofcontact switches 286, 287 and transmits commands to control module 203for execution. This avoids the necessity for the user to move a handand/or arm to touch a keypad on control module 203.

A user may require two hands to make the connections in structure 200and set control module 203 to a selected appropriate mode. However,during performance of a duct velocity traverse, one hand will suffice toexecute a proper traverse and collect accurate results of all desiredparameters by utilizing contact switches 286, 287 that are disposed onhandle 201 for activation by a finger and/or thumb of the hand holdinghandle 201. These features save time and effort, improve accuracy, andimprove safety.

Control module 203 and velocity sensing module 401 are electronicmodules have various capabilities, including wireless data transmissionand voice transmission, that allow them to be used in otherapplications. Alternatively, modules 203 and 401 may communicate via aconnecting wire.

FIG. 6 illustrates velocity sensing module 401. Velocity sensing module401 comprises total pressure inlet port 403 and static pressure inletport 405. Inlet ports 403, 405 are connected to a network of valves,sensors, and tubing as described below.

Velocity sensor module 401 comprises an enclosure 407, containing acircuit board with RF transceiver module, one or more status LED's, anda battery. One or more microcontrollers are programmed to control theLED indicator(s), power on and power-off sequences, battery powermonitoring, and sensor interface. Velocity sensor module 401 useslithium batteries which may or may not be rechargeable. In the case ofrechargeable batteries, a port is provided for attaching to an externalpower source.

FIG. 7 illustrates a block diagram of the velocity sensing module 401.Two valves 741 and 742 control the source of pressures presented to twopressure sensors 743 and 744. Control signals generated by amicrocontroller 749 allow differential pressure sensor 743 to measurevelocity pressure while differential pressure sensor 744 measures staticpressure. Microcontroller 749 is a commercially availablemicrocontroller and includes both a microprocessor and memory.

Microcontroller 749 is programmed to control valves 741, 742 in such away that the proper pressure is applied to pressure sensors 743, 744.This allows the measurement of Total Pressure, Static Pressure, orVelocity Pressure, as required by the operation in progress at any time.Microcontroller 749 also programs a regular zero reset phase, whichconnects the sensor inlet ports to each other for occasional zerooffset.

Pressure sensors 743 and 744 are commercially available solid statesensors. Each sensor 743, 744 has two piezoresistive elements mounted atan angle to each other in such a way that they avoid virtually allposition sensitivity. Rotation relative to the gravitational field willnot affect the measurement. Even more important in this application isthat sensors of this type have low zero drift and do not need to bere-zeroed before every reading, as do many pressure sensors, whichwastes time. This feature in turn allows the sensing electronics to makemultiple rapid measurements in succession, accurately. Barometricpressure sensor 747 measures barometric pressure as well as moduletemperature. Pressure sensors 743, 744 have outputs which vary dependingon the temperature of the element, so the sensors are characterizedindividually to determine correction factors related to temperature. Atemperature sensor 746 is in close proximity to pressure sensors 743,744, so that their outputs for a particular pressure input can beaccurately predicted.

Velocity sensing module 401 measures barometric pressure and transmitsthe measurement to control module 203. Control module 203 calculates airdensity from the two inputs of temperature and barometric pressure.

Velocity sensing module 401 has the ability to make 100 pressuremeasurements per second and to statistically analyze the results interms of running average, maximum, minimum, and standard deviation ofthe results. In turn, these data allow the user to know and understandthe condition of the air in the duct in great detail.

Velocity sensing module 401 has control inputs coupled to switches 286,287 such that the user by operating momentary switches 286, 287 cancontrol storage of measurement data into memory of microcontroller 749and/or display of measurement data.

Velocity sensing module 401 includes a standard port 757 for batterycharging and for uploading stored measurements to a PC spreadsheet. Inthe embodiment, the standard port is a mini-USB port.

In the embodiment shown, velocity sensing module 401 includes a radiofrequency transceiver 751 to provide wireless communication with controlmodule 203. In other embodiments, wired communication may be providedbetween velocity sensing module 401 and control module 203.

The measurements from velocity sensing module 401 are transmitted tocontrol module 203. Control module 203 includes both control inputs anda display. Control module 203 displays the current reading and thestatistics of a given sequence of readings, including average, maximum,and minimum.

FIGS. 8A, 8B, 8C illustrate exemplary display formats available atcontrol module 203. The display formats convey the air temperature,humidity (if desired), static pressure, density, and velocity. If theuser wishes, the user can input the size of the duct, and control module110 will automatically display the calculated airflow in CFM.

Velocity sensing module 401 has the ability to not only make 100pressure measurements per second but it also has the ability tostatistically analyze the results in terms of running average, maximum,minimum, and standard deviation of the results. In turn, these dataallow the user to know and understand the condition of the air in theduct in great detail

FIG. 9 illustrates the convenience of utilizing apparatus 200. A user901 taking air flow measurements in a duct 900 is able to hold andcontrol apparatus 200 in one hand while both sighting the position ofPitot tube 100 in duct 900 while observing measurement results ondisplay 200.

Pitot tube 100 is inserted through a hole in the wall of duct 900.Velocity sensor module 401 captures measurements. The measured valuesare transmitted to control module 201, which calculates and displays allof the results of interest to user 901. With the embodiment, user 901 isable to perform a velocity traverse while using only one hand, allowingthe other hand to be available for holding another tool or for graspinga fixed object for bracing and safety.

Turning now to FIG. 10, a second embodiment 1000 combines the functionsof control module 203 and velocity sensing module 401 into a control andsensing module 1001. Control module 203 and velocity sensing module 130are combined or placed back-to-back and mounted on a support arm 315.Tubes 307, 313 are arranged along support arm 315 to conduct total andstatic pressure to sensors 743, 744 via valves 741, 742. Cable 285 fromswitches 286 and 287 is also arranged along support arm 315. A sheath1090 may be employed to keep tubes 307, 313 and cable 285 neatlyrestrained along the support arm 315.

In a further embodiment, support arm 315 may be hollow, and may containtubes 307, 313 and cable 285 within it to conduct them neatly fromhandle 201 to control module 203 and sensing module 401.

In yet a further embodiment, modules 203 and 401 may be integrated intoone module.

Control module 401 may establish and maintains a network to communicatewith velocity sensing module 401 and with one or more temperaturesensing modules. Control module 401 may also have other functions,including display and storage of measurement data. Control module 401 isselectively controlled via various input devices including, but notlimited to: keys, buttons, and/or switches. Control module 401 may alsoexecute certain commands which are entered by user 901 via buttons,keys, or switches. Control module 401 may also execute certain commandswhich are entered by via microphone or thumb switch, allowing the user901 to use his hand for something else and facilitating highproductivity and safety.

It is desirable to determine how stable and how constant the velocityand flow is in duct 900. There may be surges of air in the duct systemthat occur cyclically due to fan speed variation, VAV operation, orother events. The user 901 may need to take action to prevent suchsurges.

Using system 200 it can be determined if the measured velocities andairflow is quite steady. Rapid measurements of velocity allow the userthe option of taking many more measurements than prescribed by thestandard traverse rules. A much more accurate average velocity may beobtained than would be the case if the sample size was limited to thestandard number.

Turning now to FIG. 11, duct 1110 carries airflow 1101 which must turn90 degrees abruptly at corner or bend 1103. Bend 1103 causes turbulenceand eddies, which result in the air velocity vectors 1111. In conditionssuch as these, it is difficult using prior art arrangements to achievean accurate average velocity with conventional meters and standardprocedures, which are designed for the velocity vector profile atlocation 1112, which usually develops after an extended distance ofairflow down a straight duct with no obstructions or size changes.

It is often the case that a wall 1151 or other obstruction prevents theair balancer from performing a traverse where a standard profile existssuch as shown at location 1112, and a traverse at a location such as1111 must be performed. If a standard matrix requiring four measurementsper drilled hole is used at location 1111, the average will not becorrect.

System 200 can easily take hundreds or thousands of measurements acrossthe duct and the average of the readings will much more accuratelyrepresent the true average.

Conventional meters require between one and six seconds per measurement.System 200 allows the user to take up to 100 measurements per second.

Turning now to FIG. 12 a method of measuring a multitude air velocitiesat a duct cross-section utilizing system 200 is illustrated. At step1201 system 200 is placed into a continuous measurement mode viaswitches 286, 287 on handle 200. At step 1203 Pitot tube 100 is insertedinto duct 1110 and Pitot tube portion 101 is positioned against the farduct wall 1111. The automatic continuous reading operation is initiatedat step 1205. After the automatic continuous reading operation isinitiated, Pitot tube 100 is withdrawn at a steady rate, e.g., one inchper second, at step 1207. Pitot tube 100 is marked every inchfacilitating withdrawal at a steady rate. When Pitot tube portion 101reaches lower duct wall 1113 the user stops the continuous measuringmode of system 200 via switches 286, 287. At step 1209 control module201 may display the number of measurements made and the average,minimum, and maximum.

The present invention has been described above with reference to anumber of exemplary embodiments and examples. It will be appreciated bythose skilled in the art that the particular embodiments shown anddescribed herein are illustrative of the invention and its best mode andare not intended to limit in any way the scope of the invention as setforth in the claims. It will also be appreciated by those skilled in theart that various changes and modifications may be made to theembodiments without departing from the scope of the present invention.These and other changes or modifications are intended to be includedwithin the scope of the present invention, as expressed in the followingclaims.

1. Handheld measuring apparatus comprising: an air velocity probe; and ahandle affixed to said air velocity probe, said handle configured suchthat said air velocity tube is graspable in a single hand for takingmeasurements in an airstream.
 2. Apparatus in accordance with claim 1,comprising: pressure sensing apparatus coupled to said air velocityprobe and carried by said handle, said air velocity probe, said handleand said pressure sensing apparatus comprising a unitary apparatusconfigured to be held in a single hand.
 3. Apparatus in accordance withclaim 2, wherein said unitary apparatus comprises: a microcontrollercoupled to said pressure sensing apparatus.
 4. Apparatus in accordancewith claim 3, comprising: display apparatus in communication with saidpressure sensing apparatus to display said measurements.
 5. Apparatus inaccordance with claim 3, comprising: display apparatus coupled to saidmicroprocessor for displaying said measurements, said display apparatuscarried by said handle and comprising a portion of said unitaryapparatus.
 6. Apparatus in accordance with claim 5, comprising: a memoryfor storing said measurements.
 7. Apparatus in accordance with claim 6,comprising: one or more switches carried by said handle to control saidapparatus.
 8. Apparatus in accordance with claim 5, wherein: saiddisplay is adjustable for viewing.
 9. Apparatus in accordance with claim8, comprising: movable apparatus coupled to said handle and supportingsaid display.
 10. Apparatus in accordance with claim 1, wherein: saidair velocity probe comprises a Pitot tube.
 11. Apparatus in accordancewith claim 2, wherein: said air velocity tube comprises a total pressureoutlet and a static pressure outlet.
 12. Apparatus in accordance withclaim 11, wherein: said pressure sensing apparatus comprises: one ormore solid state pressure sensors; a selectively operable valvearrangement coupled to said air velocity probe and to said one or moresolid state pressure sensors.
 13. Apparatus in accordance with claim 12,comprising: a microcontroller coupled to said pressure sensing apparatusand to said selectively operable valve arrangement for controllingoperation of said apparatus.
 14. Apparatus in accordance with claim 13,wherein: said selectively operable valve arrangement comprises aplurality of selectively operable valves coupled to one or more pressuresensors.
 15. Apparatus in accordance with claim 14, comprising: displayapparatus coupled to said microcontroller for displaying saidmeasurements, said display apparatus carried by said handle andcomprising a portion of said unitary apparatus.
 16. Apparatus inaccordance with claim 15, wherein: said microcontroller comprises amemory.
 17. Apparatus in accordance with claim 16, wherein said unitaryapparatus comprises: one or more switches carried by said handle tocontrol said apparatus.
 18. Apparatus to measure velocity pressure andstatic pressure in air handling systems, said apparatus comprising: aPitot tube for insertion into a duct, said Pitot tube comprising a totalpressure tube having a total pressure tube outlet, and a static tubehaving a static tube outlet; and a sensing module having a first inletcoupled to said Pitot tube outlet and a second inlet coupled to saidstatic tube outlet, said sensing module operable to concurrently measureair velocity pressure and air static pressure in said duct; and a handlecarrying said Pitot tube and said sensing module; said Pitot tube, saidsensing module and said handle arranged to provide a measuring unitholdable and operable in one hand.
 19. Apparatus in accordance withclaim 18, wherein: said sensing module comprises first and second solidstate differential pressure sensors.
 20. Apparatus in accordance withclaim 19, wherein: said sensing module comprises valving apparatusdisposed between said first and second inlets and said first and secondsolid state differential pressure sensors.
 21. Apparatus in accordancewith claim 20, wherein: said sensing module comprises a processor incommunication with said pressure sensors and operable to control saidvalving apparatus.
 22. Apparatus in accordance with claim 21,comprising: a control and display module; and said sensing module is incommunication with a control and display module.
 23. Apparatus inaccordance with claim 21, comprising: a display carried by said handleto display measurements
 24. Apparatus in accordance with claim 23,wherein: said display is positionally adjustable.
 25. Apparatus inaccordance with claim 18, comprising: one or more switches carried bysaid handle for controlling operation of said apparatus.
 26. Apparatusin accordance with claim 25, wherein: said sensing module comprisesfirst and second solid state differential pressure sensors. 27.Apparatus in accordance with claim 26, wherein: said sensing modulecomprises valving apparatus disposed between said first and secondinlets and said first and second solid state differential pressuresensors.
 28. Apparatus in accordance with claim 27, wherein: saidsensing module comprises a processor in communication with said pressuresensors and operable to control said valving apparatus.
 29. Apparatus inaccordance with claim 28, wherein: said sensing module is incommunication with a control and display module.
 30. Apparatus inaccordance with claim 28, comprising: a display carried by said handleto display measurements
 31. Apparatus in accordance with claim 30,wherein: said display is positionally adjustable.
 32. Apparatus inaccordance with claim 22, comprising: said sensor module and saidcontrol module are cooperatively operative to automatically concurrentlymeasure air velocity pressure and air static pressure at predeterminedtime intervals.
 33. Apparatus in accordance with claim 32, comprising:said time intervals are selected to provide a duct traverse. 34.Apparatus to measure velocity pressure and static pressure in airhandling systems, said apparatus comprising: a Pitot tube for insertioninto a duct, said Pitot tube comprising a total pressure tube having atotal pressure tube outlet, and a static tube having a static tubeoutlet; and a module having a first inlet coupled to said Pitot tubeoutlet and a second inlet coupled to said static tube outlet, saidmodule operable to concurrently measure air velocity pressure and airstatic pressure in said duct, said module comprising a display todisplay measurement data; and a handle carrying said Pitot tube and saidmodule; said Pitot tube, said module and said handle arranged to providea measuring unit holdable and operable in one hand with said displayviewable by a user of said apparatus.
 35. Apparatus in accordance withclaim 34, wherein: said module comprises at least one processor toperform predetermined calculations utilizing pressure measurementsreceived at said first and second inlets.
 36. Apparatus in accordancewith claim 35, comprising: said module comprises a memory; and saidprocessor stores calculated results in said memory.
 37. Apparatus inaccordance with claim 36, comprising: a display; and said processor isoperable to display predetermined ones of said calculated results onsaid display.
 38. Apparatus in accordance with claim 37, wherein: saidmodule is operative to automatically concurrently measure air velocitypressure and air static pressure at predetermined time intervals. 39.Apparatus in accordance with claim 38, comprising: said time intervalsare selected to provide a duct traverse